Diaphragm type accumulator having means to prevent the diaphragm from folding and crimping on itself due to changes in pressure



1963 'K. J. VON FORELL 3,075,558

DIAPHRAGM TYPE ACCUMULATOR HAVING MEANS TO PREVENT THE DIAPHRAGM FROM FOLDING AND CRIMPING 0N ITSELF DUE TO CHANGES IN PRESSURE Filed Sept. 24, 1959 l///// I!!! fA/f/I/l/I IN V EN TOR. KENNETH J. VM'FORELL' FIG. 4.

ATTORNEYS 1 preventing collapsing United States Patent '0 3,075,558 DIAPHRAGM TYPE AC'CUMULATOR HAVING MEANS TO PREVENT THE DIAPHRAGM FRGM FGLDING AND CRIIVIIING ON ITSELF DUE TO CHANGES IN PRESSURE Kenneth J. Von For-ell, 1449 S. Winona Way, Denver, Colo. Filed Sept. 24, 1959, Ser. No. 842,066 1 Claim. (Cl. 138-30) This invention relates to accumulators, and more particularly to diaphragm type accumulators for absorbing fluctuations in pressure in fluid systems.

In any fluid system where there is a change in flow of fluid through the system, there must be an accompanying change in pressure. The change in pressure may be negligible or may be quite large. In cases where the pressure change is large, for example the fluctuation of pressure due to a reciprocating piston pump, it may be harmful to the entire system. Under most circumstances the efliciency of the system is decreased by fluctuations in pressure. To absorb or smooth out fluetuations in such systems, accumulators have been developed and are commonly used. Accumulators may be of the diaphragm type, piston type or any other type in which there is a seal between the fluid of the system and some means to absorb the fluctuations, generally a compressible gas confined so as to provide an absorption of the fluctuations.

According to the present invention I have provided an eflicient and highly effective diaphragm type accumulator which utilizes a cup-shaped diaphragm which convolutes and turns back on itself forming a flexible barrier between the fluid pressure system and a gas compression system. The device of the invention provides a longlife accumulator having a positive action of diaphragm to absorb the fluctuations of the fluid system, and which will not fold on itself and crimp. The device is arranged to provide means for simply and easily varying the volume of the gas chamber to thereby vary the capacity of the accumulator without changing the essential parts and especially the diaphragm of the accumulator. Thus accumulators of difierent capacities may utilize the same diaphragm and perform in essentially the same manner.

Included among the objects and advantages of the present invention is to provide an improved diaphragm type accumulator which provides positive action of its diaphragm to prevent the diaphragm from folding and crimping on itself due to changes in the pressure. The device provides means for providing a variable gas chamber without changing the esssential parts. The accumulator of the invention includes a cup-shaped diaphragm interconnected with a spring which in operative position is normally under tension to assist in pulling the bottom of the cup upwardly so that the diaphragm may convolute and roll inside out without binding and crimping and of the sides.

These and other objects and advantages of the inven tion may be readily understood by referring to the following description and appended drawings in which:

FIG. 1 is a cross-sectional elevation of an accumulator according to the invention;

FIG. 2 is a side elevational view in cross section of an accumulator partially compressed by liquid;

FIG. 3 is a side elevational view of an accumulator according to the invention at full diaphragm deflection; and

FIG. 4 is a cross-sectional elevation of an accumulator according to the invention illustrating a variable capacity bonnet for the accumulator.

In the device illustrated in FIG. 1, a cup-shaped body 1 is provided with an outlet 2 having a threaded portion ice 3 for attachment to a pressure line. The inner end of member 2 extends into the inside of the body. The full open end of the body includes an annular flange 4 provided with an outwardly directed groove 5. A bonnet 6 provided with an annular flange 7 arranged to register with the flange 4 is provided with a groove 8. The grooves 5 and 8 are arranged to register forming an annular recess when the parts are placed together. A gas inlet valve 10 is fitted in the upper end of the bonnet 6, and the gas valve provides means for filling the assembled device with a gas under pressure and for retaining the same. A protective cover 11 is threadedly secured on the gas valve stem to protect the valve from injury. A clamp 12 which, in one form, consists of two halves of a ring provided with a groove or rabbet 14 engages flanges 4 and 7 when placed together clamping the bonnet to the body. Holes 15 in the clamp accommodate bolts (not shown in the drawings) to hold the two halves of the ring together. A generally cup-shaped diaphragm 17 having an outwardly extended flange 18 is fitted in the body 1. An 0 ring seal 19 is integrally affixed to the flange 18 and this 0 ring seats in the angular groove formed by the grooves 5 and 8 in the body and bonnet respectively.

An outer plate 20 is interconnected with the diaphragm to an inner plate 21 by means of a stud 22. A spring 23 is secured to the stud 22- and to the bottom of the gas valve 10. The spring is normally a tightly wound spring, illustrated in FIG. 3, with the coils touching. The spring in the absence of fluid or gas pressure normally maintains the diaphragm turned inside out and pulled up. When assembled and under sufficient gas pressure, the diaphragm is forced into the body with the spring pulled out under tension. Thus the gas pressure forces the cupshaped diaphragm into the configuration of FIG. 1 and maintains the spring under tension.

With the accumulator interconnected in a fluid pres-v sure system, by attaching the inlet 2 into a line of such a system, nitrogen gas, air or other gas under pressure is injected through the gas valve so that the pressure in the bonnet above the diaphragm 17 is greater than the pressure necessary to extend the spring to full extension with the outer plate contacting the bottom of the body 1 in addition to the pressure of the liquid in the hydraulic system. As liquid is forced into the accumulator, as where there is a change in velocity in the hydraulic system as by closing the valve quickly and the like, the pressure equalizes with the gas in the chamber. When such a pulsation or increase of pressure in liquid system occurs,

the gas is compressed by liquid being forced into the liquid chamber. The compression of the gas dissipates the pressure increases so that there is a dissipation of the shock energy.

In many hydraulic systems it may be desirable to store energy so that a smaller hydraulic pump may be used. This may be accomplished using an accumulator in accordance with the invention. Liquid is non-compressible and this non-compressible liquid may be used to compress the gas in the accumulator and thereby store energy. The amount of liquid that may be stored in a certain size accumulator may be determined by Boyles law of gases P V =P V The accumulator has a known volume of gas V and is precharged with pressure P Liquid from the system is pumped into the accumulator from a pump under a pressure P The gas is compressed to a volume V, and the oil volume is the difference between V -V The energy required to compress the gas may be recovered by reversing the flow of the liquid from the accumulator permitting the compressed gas to expand forcing the fluid from the fluid chamber of the accumulator.

As illustrated in FIG. 1, the accumulator gas pressure 3 exceeds the liquid pressure on the liquid system side of the accumulator. In FIG. 2 the liquid pressure has increased suihciently to partially compress the gas. As the gas volume decreases, the pressure increases tending to substantially equalize the pressure on. both sides ofv the diaphragm. The increase in liquid pressure permits a small. amount of liquid to enter the liquid chamber compressing tlie gas and forcing the cup. upwardly. Thezspring makes the diaphragm. convolute and start to. roll inside.

out. As illustrated inFLG. 3,. the. liquid pressure greatly exceeds the, gas pressure and the diaphragm is turned inside out permitting, the spring to return to its. tightly coiled position and compressing the gas. to its, smallest volume in. theaccumulator. Since the spring isv under tension when fully extended, increase of liquid pressure permits the spring to retract pulling the. plates 20, and 21 toward the top and causing the diaphragm to convolute. without collapsing and thereby preventing; crimping injury to the diaphragm.

Inthe modification illustrated inFlG. 4, the accumulator includes a body- 1 having its inlet 2. The diaphragm '17 is mounted therein. with its bottom portion retained between inner plate 21 and outer plate. 20. A spring 33 is attached to astud 22 joining thev two plates together, and. the upper endof the. spring: 33 is secured} to another stud 34. The: upper stud: 341 is, mounted on av web or spring stop 35 having a plurality of perforations 35a which is. secured internally of. an. elongated bonnet 3,6. The bonnet has, a flange 37 arrangedto register with flange 4' of the body; A groove; 38 in the flange 37 is arranged to; register with. a: groove in. the flange 4 forming a. seatfor the Oring-of the diaphragm 17.. The'upper, end of the; bonnet 36. is'provided' with a gas valve; and pro;- tective cap. 11. The. length ofifthebonnetmay; obviously, bevaried' to provide greatercapacity ofgas volume while; utilizing the same diaphragm. and body: as the. shorter bonnet illustrated in FIGS. 1. through 3;. The spring is. generally maintained. the. same length and. in: the same.

relative position so that the diaphragm may: operate in the same manner with. any sizeof accumulator.

In manufacturing the. accumulator, the body and the. bonnet must be'madeto. withstand themaximum pressure of the system on: which itis to be used. Normally, the gas: chamber otthe accumulator is. chargedlwith nitrogen gas slightly below the peak pulsation. or fluctuation. pressure. occur, the liquid from: the system flows: through the. port z into the liquid: chamber urging the diaphragmupwardly; As thev diaphragm. moves upwardly the gas pressure in the gas chamber increases duev to the reducing volume. At the point of equilibrium. the pressure on. both sides of the diaphragm is the. same. of? construction of; the: absorber must be determined by When pulsations or fluctuations of the. pressure.

Obviously, the materials 4 the system on which it is to be used. Thus in an oil hydraulic system, the diaphrgam may be made of a synthetic material capable of resisting the action of the oil. Also, such systems may be for a fluid such as water, and the like.

While the invention has been described with reference to specific embodiments, there is no intention to limit the spirit or scope of, the. invention to the precise details so set forth except insofar as defined in thefollowing claim.

I claim:

An accumulator comprising a relatively deep cupshaped body and a detachable cup-shaped bonnet of a predetermined volume larger than the volume of said body for forming a confined space with said body, the internal cross-section of the cup-shaped body and the cup-shaped bonnet being substantially identical, a cupshaped flexible diaphragmv of substantially the same. internal configuration as said body having an outwardly directed flange and an. integral 0 ring seal secured between said body and said. bonnet to form. a flexible barrier in said space, a. liquid system outlet from said body and. an air pressure system inlet, to. said bonnet, rigid means inclusive of, joined inner and outer plates spanningv a substantial. portion of the internal. cross section of the cup-shaped body secured to the; bottom. of said diaphragm for supportingsame inmovement internally or" said space so as. to cause. substantially uniform. convolution of said diaphragm when. the pressure of the liquid system is exertedthereagainst,v an. upper spring support mounted internally of and. across said. bonnet intermediatev its ends, atightlywound. coilv spring of substantially thesame crosssectional dimension as the plates and secured at. one end to said platesv and to. said support at the oppositev end in position tobemaintainedin. tension when said diaphragm is, extended away from said support under the pressure. of. gas, means for maintaining gas under pressure through.

said inlet into. said bonnet so as. to maintain said dia-- phragm in said body in normal operable position; withsaid springunder, tension: so as tocause. said: convolution of said diaphragm when the pressure of said liquid systern: is greater than. the gas pressure in said bonnet, and. means for releasably securing saidbonnet to said body with said bonnet fiangeand 0 ring forming a seal therebetween.

References Cited in thefileof thispatent UNITED. STATES PATENTS 2,13-2;952' 

